Carrier and method of manufacturing carrier

ABSTRACT

A carrier C is integrally formed of a pair of flanges opposed to each other and designed to rotatably support rotating bodies therebetween and a plurality of joints for connecting the flanges. A groove is formed on the border between the flanges and the joints, and openings are made among the joints. Engagement holes for rotatably supporting rotational shafts of rotating bodies are made in the flanges.

[0001] The disclosures of Japanese Patent Application Nos. 2000-38561filed on Feb. 16, 2000 and 2000-365175 filed on Nov. 30, 2000 includingthe specifications, drawings and abstracts are incorporated herein byreference in their entirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The invention relates to a carrier and a method of manufacturingthe carrier and, more particularly, to a carrier for rotatablysupporting rotating bodies such as gears and pulleys and a method ofmanufacturing the carrier.

[0004] 2. Description of Related Art

[0005] A planetary gear unit is generally employed in an automatictransmission of an automobile. The planetary gear unit has a sun gear, aring gear disposed around the sun gear, a planetary gear or a pinion(hereinafter referred to generically as a planetary gear) disposedbetween the sun gear and the ring gear so as to engage them, and acarrier for rotatably supporting the planetary gear.

[0006] As an example of a carrier for supporting a planetary gear or thelike of a planetary gear unit, Japanese Patent Application Laid-Open No.HEI 10-288248 discloses a planetary gear unit for an automatictransmission according to the related art of the invention. Thisplanetary gear unit has a ring gear, a sun gear and a pinion that engageone another, and a carrier for rotatably supporting the pinion. Thecarrier is composed of a boss connected to a shaft of the automatictransmission, a radially extended plate, a carrier plate formed of asalient axially protruding from the radially extended plate, and a baseplate having holes into which the salient of the carrier plate isfitted. The salient of the carrier plate is made thicker than the bossand the radially extended plate by differential-thickness press working.

[0007] In the planetary gear unit disclosed in the aforementionedpublication, as shown in FIG. 39, a carrier C′ is composed of a carrierplate 31 spline-connected to a shaft of an automatic transmission and adisc-shaped base plate 32. The carrier plate 31 is composed of adisc-shaped plate 31 a and a plurality of columns (salients) 33protruding towards the base plate 32 from the outer periphery of theplate 31 a in a direction substantially parallel to the shaft. Fittingportions 33 a with a reduced thickness are formed at the ends of thecolumns 33. The base plate 32 is constructed of an annular sheetmaterial having at its center a through-hole 32 a through which a shaft(not shown) or a sun gear (not shown) is inserted. Fitting holes 32 b,into which the fitting portions 33 a formed at the ends of the columns33 of the carrier plate 31 are fitted, are formed on the outercircumferential side of the base plate 32. The carrier plate 31 and thebase plate 32 are connected by fitting the fitting portions 33 a formedat the ends of the columns 33 into the fitting holes 32 b and weldingparts of the fitting portions 33 a fitted into the fitting holes 32 b tothe base plate 32. That is, according to this carrier, the carrier plate31 and the base plate 32 are formed individually, assembled, welded, andthen integrated. The carrier plate 31 and the base plate 32 are obtainedfrom press-worked sheet materials. The aforementioned publication alsodiscloses that the carrier plate and the base plate can be formed byforging or forging+cutting and the like instead of press working. Insuch a carrier, the pinion is inserted into the carrier among thecolumns 33 and between the carrier plate 31 and the base plate 32, andopenings 35 defining a space for engagement of tooth tops of the piniongear with the ring gear are made. According to another related art, thebase plate 32 and the carrier plate 31 having the columns 33 as in thecarrier of the aforementioned related art are formed by sintering,assembled, connected by waxing instead of welding, and then integratedinto a carrier.

[0008] In addition, according to still another related art, the carrierplate 31, the base plate 32 and the columns 33 are cast and integratedinto a carrier. In this related art, in order to ensure that opposedfaces of the carrier plate 31 and the base plate 32 are parallel to eachother, the carrier plate 31 and the base plate 32 are cut after thecarrier has been formed integrally.

[0009] However, among the aforementioned related arts, as for thecarrier disclosed in Japanese Patent Application Laid-Open No. HEI10-288248, as described above, every time a carrier is manufactured, thecarrier plate 31 and the base plate 32 that have been formedindividually need to be assembled, connected by welding or waxing, andthen integrated. For this reason, the number of manufacturing processesis great and each process requires its own plant, which causes a problemof the inability to reduce the cost.

[0010] Furthermore, for the purpose of rotatably supporting rotatingbodies, the carrier is required to guarantee a high degree of parallelprecision of the opposed faces of the carrier plate 31 and the baseplate 32. However, among the aforementioned related arts, as for the artwherein the carrier plate 31 and the base plate 32 that have been formedindividually by press working or sintering are assembled by welding orwaxing, the parallel precision of the opposed faces cannot be enhanceddue to an error caused during an assembling operation, a tolerance ofpressing during the manufacture of the carrier plate 31 and the baseplate 32, a distortion caused during sintering, welding heat at the timeof connection, or a distortion caused by waxing. In order to solve thisproblem, it can be considered to dispose a mandrel having apredetermined width between the opposed faces of the carrier plate 31and the base plate 32 after the carrier plate 31 and the base plate 32have been integrated, and swage them towards the mandrel. However, inthe aforementioned related art, since a welded portion or a waxedportion for connecting the carrier plate 31 and the base plate 32cracks, it is impossible to perform swaging.

[0011] Further, among the aforementioned related arts, in the case wherethe carrier plate 31 and the base plate 32 that have been formedindividually are assembled by welding, since it is necessary to preventthe fitting portions 33 a of the columns 33 and the base plate 32 havingthe fitting holes 32 b from being melted down during welding andguarantee sufficient rigidity, it is impossible to thin at least thebase plate 32 and the columns 33 or narrow the peripheries of thecolumns 33. This makes it impossible to save the weight of the carrier.

[0012] In addition, in the case where the columns 33 of the carrierplate 31 and the base plate 32, which have been pressed, are assembledby welding, since the carrier plate 31 and the base plate 32 have beenformed individually, the interrupted flow of a material causes a problemof low rigidity. In the case where the columns 33 of the carrier plate31 and the base plate 32, which have been formed by sintering, areassembled by welding, since powder materials with a low density are usedand there is no material flow, there is caused a problem of much lowerrigidity.

[0013] Among the aforementioned related arts, as for the carrier intowhich the carrier plate, the base plate and the joints are cast andintegrated, it is necessary to cut the carrier plate and the base plateafter the carrier has been formed integrally. For this reason, thenumber of manufacturing processes increases and materials are wasted,which causes a problem of an increase of the cost. Because the carrierthat has been formed by casting is obtained simply by forming a moltenmaterial and a density of contents of the carrier is low and there is nomaterial flow, there is caused a problem of even lower rigidity.

[0014] Because of the problem of low rigidity as described above,namely, the problem of low rigidity per unit weight, the carrier thathas been manufactured by sintering or forging needs to be made thick soas to guarantee predetermined rigidity. This causes problems of morewasted materials and the inability to save the weight of the carrier.

SUMMARY OF THE INVENTION

[0015] The invention has been made in consideration of theaforementioned problems. It is an object of the invention to provide acarrier having a construction capable of enhancing parallel precision ofopposed faces with a reduced number of processes and saving the weightthrough increased rigidity. It is also an object of the invention toprovide a carrier having a construction that makes its manufacture easy.

[0016] Furthermore, with a view to solving the aforementioned problems,it is also an object of the invention to provide a method ofmanufacturing a carrier wherein the number of manufacturing processescan be reduced with a simple structure, wherein the parallel precisionof opposed faces can be enhanced easily, and wherein the weight can besaved through increased rigidity.

[0017] In order to achieve the aforementioned objects, there is provideda carrier according to a first aspect of the invention wherein a pair offlanges opposed to each other and designed to rotatably support rotatingbodies therebetween and joints for connecting the flanges are integrallyformed through plastic deformation of a single material.

[0018] In the carrier according to the first aspect of the invention,the flanges and the joints are integrally formed through plasticdeformation of a single material with uninterrupted flow of thematerial. Therefore, the number of parts is reduced and the processes ofassembling and bonding become unnecessary so that the carrier is formedwith a reduced number of processes. Thus, the parallel precision of theopposed faces is enhanced at a low cost, and the weight can be savedthrough high rigidity.

[0019] The joints may be disposed along outer peripheries of theflanges.

[0020] Because the joints are disposed along the outer peripheries ofthe flanges, there is provided a carrier suited to support, as rotatingbodies that are rotatably supported, planetary gears engaging sun gearsin an automatic transmission. In this case, a plurality of joints aredisposed along the circumference of the flanges discontinuously, andopenings are made among the joints. Holes through which shafts forsupporting the sun gears are inserted are formed at the centers of theflanges.

[0021] Furthermore, a groove may be formed on a border between theflanges and the joints.

[0022] If the groove is formed on the border between the flanges and thejoints especially on the side of the inner surface of the carrier, theprocess of bending is guided by the groove and the border between theflanges and the joints is formed with high precision. Therefore, anintegral-type carrier having a construction that makes its manufactureeasy is provided.

[0023] In a method of manufacturing a carrier according to anotheraspect of the invention, a material is formed into the shape of a cuphaving an opening, and the opening of the cup is closed off so that apair of flanges opposed to each other and designed to rotatably supportrotating bodies therebetween and joints for connecting the flanges areintegrally formed.

[0024] According to this aspect of the invention, after the material hasbeen formed into the shape of a cup, the material is closed off so thatthe end faces of the opening in the cup are shrunk radially inwardly.Thereby it becomes easy to manufacture a carrier having a pair offlanges opposed to each other and designed to rotatably support rotatingbodies therebetween and joints for connecting the flanges. Besides,since the flanges and the joints are integrally formed from a singlematerial with uninterrupted flow of the material, the number of parts isreduced and the processes of assembling and bonding become unnecessaryso that the carrier is formed with a reduced number of processes. Thus,there is provided a method of manufacturing a carrier wherein theparallel precision of opposed faces can be enhanced at a low cost andwherein the weight can be saved through high rigidity. A bottom of thematerial formed into the shape of the cup is turned into one of theflanges. Peripheral walls adjacent to the bottom are turned into thejoints. An opening-side portion of the cup-shaped material, which is tobe closed off, is turned into the other flange. Thus, according to theinvention, a carrier of a configuration wherein joints are integratedwith the outer peripheries of flanges is manufactured.

[0025] The material is selected from a plate material, a rod materialand a tubular material.

[0026] By selecting one of a plate material, a rod material and atubular material, a method of manufacturing a carrier easily is providedin a more concrete form. In the case where a plate material is used, thematerial can be formed into the shape of a cup by being bent and/ordrawn. In the case where a tubular material is used, the material can beformed into the shape of a cup by shrinking one end of the material. Inthe case where a rod material is used, the material can be formed intothe shape of a cup by being extruded.

[0027] In a method of manufacturing a carrier according to anotheraspect of the invention, both end openings of a tubular material areclosed off, whereby a pair of flanges opposed to each other and designedto rotatably support rotating bodies therebetween and joints forconnecting the flanges are formed integrally.

[0028] According to this aspect of the invention, both end faces ofopenings of a tubular material are simultaneously closed off so thatthey are shrunk radially inwardly. Thereby a carrier having a pair offlanges opposed to each other and designed to rotatably support rotatingbodies therebetween and joints for connecting the flanges ismanufactured easily. Besides, since the flanges and the joints areintegrally formed from a single material with uninterrupted flow of thematerial, the number of parts is reduced and the processes of assemblingand bonding become unnecessary so that the carrier can be formed with areduced number of processes. Thus, there is provided a method ofmanufacturing a carrier wherein the parallel precision of opposed facescan be enhanced at a low cost and wherein the weight can be savedthrough high rigidity. Axial centers of a side wall of the tubularmaterial are turned into the joints of the carrier, and both axial endsof the side wall of the tubular material, which are to be closed off,are turned into a pair of flanges. Thus, according to the invention, acarrier having a configuration wherein joints are integrated with theouter peripheries of flanges is manufactured.

[0029] A bending guide such as a groove may be formed on a borderbetween pre-joints and the other pre-flange before the material isclosed off.

[0030] By forming the bending guide, the process of bending is guided bythe guide precisely when the material is closed off. Therefore, theparallel precision and the dimensional precision of the opposed faces ofthe flanges are further enhanced.

[0031] Openings may be made in pre-joints of the material before thematerial is closed off.

[0032] If the openings are made, the outer peripheral faces of theflanges are curved towards the inside of the openings when the materialis closed off. That is, the openings are made in the joints withoutaffecting the parallel precision of the opposed faces of the flanges.Therefore the parallel precision of the opposed faces is furtherenhanced. In the case where a plate material is used, the openings aremade by forming the contour of the material and trimming it at the sametime. Thus, the number of processes can be further reduced.

[0033] In addition, mandrels may be inserted from the openings made inthe pre-joints of the material so as to close off the material.

[0034] The material is closed off with the mandrels inserted into thepre-joints of the material from the openings that have been made,whereby it becomes possible to close off the material from its preciseposition and further enhance the parallel precision and the dimensionalprecision of the opposed faces of the flanges.

[0035] Engagement holes for engagement with rotational shafts forrotatably supporting rotating bodies in the carrier may be made inpre-flanges before the material is closed off.

[0036] If the engagement holes are made in advance in the pre-flanges ofthe material, the parallel precision of the opposed faces of the flangesis not affected by the pressing force or the like generated at the timewhen the engagement holes are made. Thus, the parallel precision of theopposed faces is further enhanced. In addition, if a plate material isused, the engagement holes are made by forming the contour of thematerial and trimming it at the same time. Thus, the number of processescan be further reduced.

[0037] In a method of manufacturing a carrier according to still anotheraspect of the invention, a wall surface at the axial center of thetubular material is bulged radially outwardly so that a pair of flangesopposed to each other and designed to rotatably support rotating bodiestherebetween and joints for connecting the flanges are integrallyformed.

[0038] According to this aspect of the invention, the center of atubular material is bulged, whereby a carrier having a pair of flangesopposed to each other and rotatably supporting rotating bodiestherebetween and joints for connecting the flanges is manufacturedeasily. Besides, since the flanges and the joints are integrally formedfrom a single material with uninterrupted flow of the material, thenumber of parts is reduced and the processes of assembling and bondingbecome unnecessary so that the carrier can be formed with a reducednumber of processes. Thus, the parallel precision of the opposed facescan be enhanced at a low cost, and the weight can be saved through highrigidity. Bulged axial centers of the tubular material are turned intothe joints of the carrier, and both axial ends of the tubular materialare turned into a pair of flanges. Thus, according to this aspect of theinvention, a carrier having a configuration wherein joints areintegrated with the outer peripheries of the flanges is manufactured.

[0039] Openings may be made in pre-joints of the material before thematerial is bulged.

[0040] If the openings are made in the pre-joints at the centers of thetubular material before the tubular material is bulged, the outerperipheral end faces of the flanges are curved towards the inside of theopenings when the material is bulged. That is, the openings are made inthe joints without affecting the parallel precision of the opposed facesof the flanges. Thus, the parallel precision of the opposed faces can befurther enhanced.

[0041] Engagement holes for engagement with rotational shafts forrotatably supporting rotating bodies in the carrier are made inpre-flanges before the material is bulged.

[0042] If the engagement holes are made in advance in the pre-flanges ofthe material, the parallel precision of the opposed faces of the flangesis not affected by the pressing force or the like generated at the timewhen the engagement holes are made. Thus, the parallel precision of theopposed faces can be further enhanced.

[0043] Furthermore, mandrels may be interposed in positions for mountingrotating bodies between the flanges so that the flanges are swagedtowards the mandrels.

[0044] If the process of swaging is performed with the mandrelsinterposed in the positions for mounting rotating bodies between theflanges, there is provided a method of manufacturing a carrier whereinthe parallel precision and the dimensional precision of opposed faces atpositions for mounting rotating bodies between flanges can be furtherenhanced. In the case where openings are made in advance in portions ofa material, which are turned into joints in one of the followingprocesses, before the material is formed in a predetermined manner,mandrels can be inserted from the openings easily.

BRIEF DESCRIPTION OF THE DRAWINGS

[0045]FIG. 1 is a plan view of a carrier according to one embodiment ofthe invention.

[0046]FIG. 2 is a cross-sectional view taken along a line II-II shown inFIG. 1.

[0047]FIG. 3 is a cross-sectional view of a carrier according to anotherembodiment of the invention.

[0048]FIG. 4 is a cross-sectional view of a carrier according to stillanother embodiment of the invention.

[0049]FIG. 5 is a plan view of a plate material for explaining a methodof manufacturing a carrier according to the invention.

[0050]FIG. 6 is a cross-sectional view taken along a line VI-VI shown inFIG. 5.

[0051]FIG. 7 is a plan view of a state where a pilot hole and engagementholes are made in one pre-flange of the plate material shown in FIG. 5and where auxiliary openings and reference holes are made in pre-jointsof the plate material shown in FIG. 5.

[0052]FIG. 8 is a cross-sectional view taken along a line VIII-VIIIshown in FIG. 7.

[0053]FIG. 9 is a plan view of a state where the engagement holes in theplate material shown in FIG. 7 are chamfered.

[0054]FIG. 10 is a cross-sectional view taken along a line X-X shown inFIG. 9.

[0055]FIG. 11 is a plan view of a state where the pilot holes in theplate material shown in FIG. 9 are formed into through-holes and wherethe engagement holes in the plate material shown in FIG. 9 are finishedto a dimension allowing engagement with rotational shafts of rotatingbodies.

[0056]FIG. 12 is a cross-sectional view taken along a line XII-XII shownin FIG. 11.

[0057]FIG. 13 is a plan view of a cup-shaped material that has beenformed by bending and drawing the plate material shown in FIG. 11.

[0058]FIG. 14 is a cross-sectional view taken along a line XIV-XIV shownin FIG. 13.

[0059]FIG. 15 is a plan view of a state where a groove designed as abending guide is formed on the border between pre-joints and the otherpre-flange on the inner periphery of a wall of the cup-shaped materialshown in FIG. 13.

[0060]FIG. 16 is a cross-sectional view taken along a line XVI-XVI shownin FIG. 15.

[0061]FIG. 17 is a plan view of a state where front-end openings in thewall of the cup-shaped material shown in FIG. 15 are preliminarilyclosed off at an appropriate angle from the groove so that the front-endopenings are slightly shrunk radially inwardly.

[0062]FIG. 18 is a cross-sectional view taken along a line XVIII-XVIIIshown in FIG. 17.

[0063]FIG. 19 is a plan view of a state where mandrels are insertedthrough the openings preliminarily closed off as shown in FIG. 17 sothat the front-end openings in the wall are shrunk radially inwardly.

[0064]FIG. 20 is a cross-sectional view taken along a line IIX-IIX shownin FIG. 19.

[0065]FIG. 21 is a plan view of a state where engagement holes are madein the other flange of the material shown in FIG. 19.

[0066]FIG. 22 is a cross-sectional view taken along a line IIXII-IIXIIshown in FIG. 21.

[0067]FIG. 23 is a plan view of a state where the engagement holes shownin FIG. 21 are chamfered.

[0068]FIG. 24 is a cross-sectional view which is taken along a lineIIXIV-IIXIV shown in FIG. 23 and which also shows a chamfering machineaccording to one embodiment of the invention.

[0069]FIG. 25 is a plan view of a state where the engagement holeschamfered as shown in FIG. 23 are finished to a dimension allowingengagement with rotational shafts of rotating bodies.

[0070]FIG. 26 is a cross-sectional view taken along a line IIXVI-IIXVIshown in FIG. 25.

[0071]FIG. 27 is a plan view of a state where mandrels are inserted fromopenings made in the joints of the carrier shown in FIG. 25 throughpositions for mounting rotating bodies between both the flanges andwhere both the flanges are swaged towards the mandrels.

[0072]FIG. 28 is a cross-sectional view taken along a lineIIXVIII-IIXVIII shown in FIG. 27.

[0073]FIG. 29 is a cross-sectional view of a pressing machine accordingto one embodiment of the invention in a state where the preliminarilyclosed-off material is being closed off.

[0074]FIG. 30 is a cross-sectional view of a pressing machine accordingto one embodiment of the invention in a state where the material shownin FIG. 29 has been closed off.

[0075]FIG. 31 is a cross-sectional view of a method of manufacturing acarrier according to a second embodiment of the invention.

[0076]FIG. 32 is a cross-sectional view of a method of manufacturing acarrier according to a third embodiment of the invention.

[0077]FIG. 33 is a cross-sectional view of a method of manufacturing acarrier according to a fourth embodiment of the invention.

[0078]FIG. 34 is a cross-sectional view of a method of manufacturing acarrier according to a fifth embodiment of the invention.

[0079]FIG. 35 is a cross-sectional view of a method of manufacturing acarrier according to a sixth embodiment of the invention.

[0080]FIG. 36 is a cross-sectional view of a method of manufacturing acarrier according to a seventh embodiment of the invention.

[0081]FIG. 37 is a cross-sectional view of a method of manufacturing acarrier according to an eighth embodiment of the invention.

[0082]FIG. 38 is a cross-sectional view of a method of manufacturing acarrier according to a ninth embodiment of the invention.

[0083]FIG. 39 is a cross-sectional view of a carrier according to therelated art.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0084] First of all, a carrier according to one embodiment of theinvention will be described in detail with reference to FIGS. 1, 2,which show a carrier C for rotatably supporting planetary gears (notshown) as rotating bodies in a planetary gear unit of an automatictransmission employed in an automobile and the like as described above.In the following description, like reference numerals denote like orsimilar components.

[0085] The carrier C of the invention is integrally formed of a pair offlanges 1, 2 and a plurality of joints 3 through plastic deformation ofa single material. The flanges 1, 2 are opposed to each other androtatably support rotating bodies therebetween. The joints 3 connectboth the flanges 1, 2. A groove 4 is formed on the border between theflanges 1, 2 and the joints 3. The carrier C has openings 5 for exposingplanetary gears so that the planetary gears and the like are insertedinto the carrier C among the joints 3 and that the planetary gears canengage ring gears (not shown). Engagement holes 6, 7 for rotatablysupporting rotational shafts of rotating bodies are made in the flanges1, 2 of the carrier C respectively.

[0086] Each of the flanges 1, 2, which constitute a pair, is formedgenerally in the shape of a disc. In this embodiment, through-holes 1 a,2 a, through which shafts (not shown) and sun gears (not shown) areinserted, are made at the centers of the flanges 1, 2 respectively. Theflanges 1, 2 of the invention function substantially in the same manneras the carrier plate 31 and the base plate 32 of the carrier C′ of theaforementioned related art. A plurality of joints 3 are formed alongouter peripheral edges of the flanges 1, 2 in the direction parallel toan axis J-J so as to retain opposed faces of the flanges 1, 2 at apredetermined distance. The joints 3 of the invention functionsubstantially in the same manner as a plurality of columns 33 protrudingtowards the base plate 32 substantially in the direction parallel to theshafts from the outer periphery of the plate portion 3 a of the carrierplate 31 of the carrier C′ of the aforementioned related arts.

[0087] In the embodiment shown in FIG. 1, the flanges 1, 2 respectivelyhave the three engagement holes 6, 7 for engagement with rotationalshafts (not shown) for rotatably supporting planetary gears. Thus, inthis embodiment, the three joints 3 are disposed along the outerperipheral edges of the flanges 1, 2 substantially at the centers withrespect to the circumferential direction of the engagement holes 6, 7.In addition, reference holes 8 used as a positioning reference or thelike are made in the joints 3 of the carrier C of this embodimentsubstantially at the centers with respect to the axial direction and thecircumferential direction of the joints 3.

[0088] The carrier C having such a structure can be formed throughplastic deformation of a single material, for example, by spinning ordrawing a plate material W using a tool such as a spatula or a pressroller. Because the thus-formed carrier C is integrally formed of theflanges 1, 2 and the joints 3 with uninterrupted flow of a material, itis possible to reduce the number of parts and form the carrier C with areduced number of processes, namely, without the necessity of performingassembling and bonding processes. Furthermore, the parallel precision ofthe opposed faces of the flanges 1, 2 can be enhanced at a low cost.Because the carrier demonstrates high rigidity, it is possible to reducethe thickness of the carrier and thus realize a structure allowing theweight saving of the carrier. As will be described later, if the carrierC is formed from the plate material W by drawing, the groove 4 ispreliminarily formed in a portion which is to be the inside of thecarrier and which is to be a border between the joints 3 and at leastone of the flanges 1, 2 of the material W either along the entirecircumference or discontinuously. Thereby, when the material W is closedoff, it is urged to be bent along the groove 4. Therefore, the borderbetween at least one of the flanges 1, 2 and the joints 3 is bentprecisely. Accordingly, the parallel precision of the opposed faces ofthe flanges 1, 2 is further enhanced.

[0089] The carrier C according to the invention is not limited to thisembodiment. For example, in the case of the carrier C employed in theplanetary gear unit or the like of the automatic transmission of theautomobile as mentioned above, it is possible to integrally form a boss9 so that it continues from the through-hole 1 a or 2 a formed at thecenter of at least one of the flanges 1, 2 as shown in FIG. 3 in case ofnecessity, and form a spline or a gear 10 in the integrally formed boss9 as shown in FIG. 4. The carrier C of the invention is not necessarilyemployed in a planetary gear unit of an automatic transmission for anautomobile or the like. That is, the carrier C according to theinvention is applicable to other purposes.

[0090] The thus-constructed carrier C of the invention eliminates thenecessity to assemble the columns 33 of the carrier plate 31 with thebase plate 32 as is the case with the carrier C′ of the related arts(see FIG. 39). Thus, the parallel precision is not adversely affected bythe forming tolerance or the assembling error of the carrier plate 31and the base plate 32. The opposed faces of the flanges 1, 2 are formedwith a high degree of parallel precision.

[0091] Next, a method of manufacturing the carrier C according to oneembodiment of the invention will be described in detail with referenceto FIGS. 5 through 28, which show a case where the carrier C constructedas described above is manufactured.

[0092] In the method of manufacturing the carrier C according to theinvention, the carrier C having the flanges 1, 2 and rotatablysupporting rotating bodies such as planetary gears between the flanges1, 2 is manufactured. In this embodiment, the plate material W is bentand drawn into the shape of a cup, whereby the flange 1 is formedsubstantially at the center of the plate material W and a wall 11 (e.g.see FIG. 14) is formed on the outer periphery of the flange 1. Afront-end opening in the wall 11 formed of an outer peripheral end faceWa of the material W is closed off, and the joints 3 and the flange 2are integrally formed so that they continue from the flange 1. When thefront-end opening of the material W formed into the shape of a cup or atube (described later) is “closed off”, it is formed so as to be shrunkradially inwardly.

[0093] Furthermore, in the method of manufacturing the carrier Caccording to the invention, among a series of the aforementionedprocesses, auxiliary openings 5′ (e.g. see FIG. 11) or the openings 5through which rotating bodies or the like can be inserted into thecarrier C are made in pre-joints (3) of the plate material W before theplate material W is bent and drawn into the shape of a cup, and theengagement holes 6 for engagement with rotational shafts for rotatablysupporting planetary gears designed as rotating bodies in the carrier Care made in at least one of pre-flanges (1). Further, the bending guide4 is formed on the border between the joints 3 and at least one of thepre-flanges (1), (2) (e.g. see FIG. 16) before the material W is closedoff, and closing-off mandrels 12 are inserted from the openings 5 madein the pre-joints (3) of the material W that has been bent and drawninto the shape of a cup (e.g. see FIG. 19). The outer peripheral endface Wa of the cup-shaped material W is closed off so as to be shrunkradially inwardly. Furthermore, swaging mandrels 13 are inserted intomounting positions of the rotating bodies between the flanges 1, 2 fromthe openings 5 made in the joints 3 of the closed-off carrier C (e.g.see FIG. 27), and the flanges 1, 2 are swaged towards the swagingmandrels 13.

[0094] Hereinafter, a series of manufacturing processes according tothis embodiment of the invention will be described in detail. The platematerial W of this embodiment is generally formed into the shape of adisc having a predetermined thickness as shown in FIGS. 5, 6. Asindicated by chain lines in FIG. 5, the central portion of the platematerial W corresponds to the pre-flange (1), and the outer peripheraledge of the plate material W corresponds to the pre-flange (2). Anannular portion located between the central portion (1) and the outerperipheral edge (2) in the radial direction corresponds to thepre-joints (3).

[0095] As shown in FIGS. 7, 8, a generally triangular pilot hole 1 a′ ismade at the center of the pre-flange (1) of the thus-formed platematerial W, and three auxiliary holes 6′, which are to be the engagementholes 6, are made around the pilot hole 1 a′. For a later-describedreason, the auxiliary holes 6′ are set in a dimension slightly smallerthan a dimension allowing engagement with the rotational shafts of theplanetary gears. The three auxiliary openings 5′ are made in thepre-joints (3) radially outwardly so as to correspond to the auxiliaryholes 6′. The three reference holes 8 are made at the centers in thecircumferential direction of the auxiliary openings 5′ and slightlyradially outwardly of the auxiliary openings 5′. The radial dimension ofthe auxiliary openings 5′ is set to almost half of the width of thejoints 3 (the distance between the flanges of the carrier). Then, moreprocesses are performed to form the openings 5 through which planetarygears or the like can be inserted into the carrier C thus manufactured.

[0096] Then, as shown in FIGS. 9, 10, after the auxiliary holes 6′ havebeen made, the plate material W is chamfered by press working, cuttingoperations or the like so that the peripheries of sides of the auxiliaryholes 6′ which are to be the inside of the carrier C are inclined with adiameter gradually increasing towards the inside of the carrier C. Thedimension of the auxiliary holes 6′ made in advance changes because ofthe chamfering. The chamfering means that the side of the auxiliaryholes 6′ which is to be the inside of the carrier C is scraped off.

[0097] Then, as shown in FIGS. 11, 12, the plate material W is punchedso that the periphery of the pilot hole 1 a′ assumes a generallycircular shape, and one of the through-holes 1 a through which shafts(not shown) and sun gears (not shown) are inserted is made. A notch 14as a mark is made in the circular through-hole 1 a for example for thepurpose of detecting the rotational phase of the formed carrier C in thecircumferential direction. The chamfered auxiliary holes 6′ are finishedinto the engagement holes 6 having a dimension allowing engagement withthe rotational shafts of the planetary gears.

[0098] Then, as shown in FIGS. 13, 14, the plate material W is bent anddrawn into the shape of a cup by means of pressing or the like, and theflange 1 and the wall 11 extending substantially perpendicularly to theouter periphery of the flange 1 are formed. By being closed off in oneof the following processes, the wall 11 constitutes the joints 3 and theother flange 2. The auxiliary openings 5′ made in advance have almosthalf of the height of the pre-joints (3) extending from the outerperipheral edge of the flange 1 to the wall 11.

[0099] Then, as shown in FIGS. 15, 16, in order to ensure that planetarygears (not shown) or the like can be inserted into thelater-manufactured carrier, the auxiliary openings 5 are punched on thefront-end side of the wall 11 to a predetermined height and formed intothe openings 5. At the same time or almost simultaneously, the groove 4designed as a bending guide is formed on the border between thepre-flange (2) and the pre-joints (3) on the inner periphery of the wall11 either along the entire circumference or discontinuously.

[0100] Then, as shown in FIGS. 17, 18, the wall 11 is preliminarilyclosed off at an appropriate angle from the groove 4 so that thefront-end opening in the wall 11 (the outer peripheral end face Wa ofthe material W) is slightly shrunk radially inwardly.

[0101] Thereafter, according to this embodiment, as shown in FIGS. 19,20, each of the closing-off mandrels 12 is inserted from one of theopenings 5 to another one adjacent thereto so as to be close to acorresponding one of the joints 3, and pressed by a pressing machineshown in FIGS. 29, 30. The material W is then closed off so that thefront-end opening in the wall 11 (the cup-shaped opening defined by theouter peripheral end face Wa of the material W) is shrunk radiallyinwardly, until the pre-flange (2) becomes parallel to the flange 1.

[0102] A pressing machine for closing off the preliminarily closed-offmaterial according to an embodiment of the invention will be described.As shown in FIGS. 29, 30, the pressing machine has an upper mold 40 anda lower mold 41, which are vertically movable relative to each other.The upper mold 40 has a punch 42, which presses the front-end opening Waof the preliminarily closed-off material W when the upper mold 40 isrelatively close to the lower mold 41. The lower mold 41 has a die 43for accommodating the preliminarily closed-off material W, an ejector 44slidably fitted into the die 43 to support the material W, and anejector rod 45 for vertically moving the ejector 44 in the die 43. Theinner diameter of the die 43 is approximately equal to the diameter of abottom of the cup-shaped material W, which is to be the flange 1.Although not shown, holes are made in the die 43 so as to correspond tothe openings 5 made between the joints 3 of the material W. Theclosing-off mandrels 12 can be inserted into the openings 5 in thematerial W through the holes (see FIG. 19). The height of theclosing-off mandrels 12 is approximately equal to the distance betweenthe inner faces of the flanges 1, 2 of the carrier C.

[0103] When the preliminarily closed-off material W is closed off, thematerial W is first accommodated in the die 43 with the upper mold 40and the lower mold 41 being spaced apart from each other, and theclosing-off mandrels 12 are inserted from the openings 5. In this state,if the upper mold 40 and the lower mold 41 are moved towards each other,the punch 42 presses the front-end opening Wa of the preliminarilyclosed-off material W as shown in FIG. 29. Thereby the preliminarilyclosed-off material W is bent so that the front-end opening Wa of thematerial W is shrunk radially inwardly, until the wall 11 extendssubstantially at a right angle from the groove 4, namely, until the wall11 becomes parallel to the flange 1. Thus, the portions among theopenings 5 in the circumferential direction constitute the joints 3, andthe portion (2) which substantially forms a right angle with the joints3 and which extends parallel to the flange 1 constitutes the flange 2.That is, the foregoing processes are performed to integrally form thejoints 3 and the flange 2 so that they continue from the flange 1. Theclosed-off front-end opening (the outer peripheral end face Wa)constitutes the through-hole 2 a through which a shaft (not shown) or asun gear (not shown) is inserted. At this moment, especially thefront-end opening Wa of the closed-off material W generally tends to becrimpled because the material is compressed in the circumferentialdirection by being shrunk. However, the material W is thick enough todemonstrate rigidity for preventing especially the front-end opening Wafrom being crimpled but is thin enough to sufficiently save the weightof the carrier C. In addition, according to the invention, since thepre-flange (2) of the wall 11 is pressed so as to be sandwiched betweenthe closing-off mandrels 12 and the punch 42 as shown in FIG. 30, thematerial W is prevented from being crimpled. Because the auxiliaryopenings 5′ and the openings 5 are made in advance before the material Wis bent and drawn, the end faces of the flanges 1, 2 facing the openings5 are not curved so as to face each other. Because the flanges 1, 2 andthe joints 3 are integrally formed with uninterrupted flow of thematerial W, the carrier C is formed with high rigidity. For this reason,the flanges 1, 2 and the joints 3 can be made relatively thin, wherebyit becomes possible to save the weight of the carrier C. After thematerial W has been closed off, the upper mold 40 and the lower mold 41are moved away from each other. The ejector 44 is then raised withrespect to the die 43 by driving the ejector rod 45, and the thus-formedcarrier C is fetched from the die 43.

[0104] Thereafter, as shown in FIGS. 21, 22, auxiliary holes 7′ are madein the flange 2 of the carrier C so as to correspond to the engagementholes 6 made in the flange 1. As is the case with the auxiliary holes 6′(see FIGS. 7, 8) first made in the flange 1, the auxiliary holes 7′ areset in a dimension slightly smaller than a dimension allowing engagementwith the rotational shafts of the planetary gears. As is the case withthe engagement holes 6 in the flange 1, as shown in FIGS. 23, 24, afterthe auxiliary holes 7′ have been made, the material W is chamfered sothat the peripheries of sides of the auxiliary holes 7′ which are to bethe inside of the carrier C are inclined with a diameter graduallyincreasing towards the inside of the carrier C.

[0105] The auxiliary holes 7′ can be chamfered using a chamferingmachine 20 as shown in FIG. 24. The chamfering machine 20 has a mastercam member 21 inserted into the carrier C through one of the openings 5,an auxiliary cam member 22 longitudinally movably supported in themaster cam member 21, and a chamfering punch 23 protruded from themaster cam member 21 by the auxiliary cam member 22. One end face 21 aof the master cam member 21 is inclined in the shape of a cam so thatthe chamfering punch 23 moves into the opening 5 and faces acorresponding one of the auxiliary holes 7′ as a cam 24 movesvertically. The chamfering punch 23, which faces one of the engagementholes 7 to be chamfered, is retained at the other end of the master cammember 21 such that the chamfering punch 23 can protrude therefrom. Endfaces 22 a, 22 b of the auxiliary cam member 22 are inclined in theshape of a cam, and an insertion hole 21 c is made in the master cammember 21 at the end on the side of the cam-shaped end face 21 a so thata cam 25 can press the cam-shaped end face 22 a of the auxiliary cammember 22. Furthermore, an end face 23 a of the chamfering punch 23located in the master cam member is inclined in the shape of a cam so asto correspond to the inclination of the end face 22 b of the auxiliarycam member 22. The other end face 23 b of the chamfering punch 23 isformed so as to correspond to a shape into which the engagement holes 7are chamfered. In the thus-constructed chamfering machine 20, the mastercam member 21 is disposed so as to correspond to one of the openings 5between the joints 3. If the cam-shaped end face 21 a of the master cammember 21 is pressed by the cam 24 that is vertically driven by apressing machine (not shown), the chamfering punch 23 moves so as tomatch a corresponding one of the unchamfered auxiliary holes 7′ and themaster cam member 21 is inserted into a space between the flanges 1, 2through the opening 5 of the joints 3. At this moment, the cam-shapedend face 22 a of the auxiliary cam member 22 on the side of theinsertion hole 21 c is not being pressed by the cam 25. Accordingly, thechamfering punch 23 is accommodated in the master cam member 21 withoutprotruding therefrom.

[0106] Thereafter, if the cam-shaped end face 22 a of the auxiliary cammember 22 on the side of the insertion hole 21 a is pressed by the cam25, the chamfering punch 23 protrudes from the master cam member 21.After the auxiliary holes 7′ have been made, the peripheries of theirsides which are to be the inside of the carrier C are inclined with adiameter gradually increasing towards the inside of the carrier C andchamfered.

[0107] After completion of the aforementioned chamfering of theauxiliary holes 7′, the auxiliary holes 71 that have changed indimension by being chamfered are finished into the engagement holes 7having a dimension allowing engagement with the rotational shafts of theplanetary gears, as shown in FIGS. 25, 26.

[0108] Finally in the thus-formed carrier C, as shown in FIGS. 27, 28,while the swaging mandrels 13 are inserted through the openings 5 anddisposed in positions which are between the flanges 1, 2 and which arearound the engagement holes 6, 7 for engagement with the rotationalshafts of the planetary gears, namely, positions which at least serve tomount the rotating bodies, the flanges 1, 2 are coined towards theswaging mandrels 13 by a press (not shown) or the like, as shown inFIGS. 27, 28. Coining means a process of finishing the flanges whilepressing them by means of a press or the like for the purpose ofeliminating the surface roughness of the flanges. At the same time,coining helps enhance the parallel precision of the flanges 1, 2. Theswaging mandrels 13 have parallel faces which are opposed to the flanges1, 2. The width (height) of the faces is set so as to substantiallycoincide with a desired distance between the opposed faces of theflanges 1, 2 of the carrier C. Thus, according to the invention, theflanges 1, 2 and the joints 3 are integrally formed and the opposedfaces of the flanges 1, 2 of the carrier C are swaged towards theswaging mandrels 13, whereby it becomes possible to form the carrier Cwith high degrees of parallel precision and dimensional precision.

[0109] In the thus-formed carrier C, planetary gears are inserted into aspace between the flanges 1, 2 from the openings 5, and the ends ofrotational shafts of the planetary gears engage the engagement holes 6,7 made in the flanges 1, 2 respectively. The planetary gears arerotatably and stably supported with their rotational shafts beingsupported by both the flanges 1, 2 which demonstrate a high degree ofparallel precision.

[0110] Methods of manufacturing a carrier according to other embodimentsof the invention will be described with reference to FIGS. 31 through38. The description of the following embodiments will be focused on whatis different from the aforementioned embodiment. The components similarto or corresponding to those in the aforementioned embodiment will bedenoted by the same reference numerals, and the description of thecomponents or the detailed description and graphical representation ofthe components will be omitted.

[0111]FIG. 31 shows a method of manufacturing the carrier C according toa second embodiment of the invention. FIG. 32 shows a third embodimentof the invention. FIG. 33 shows a fourth embodiment of the invention.FIG. 34 shows a fifth embodiment of the invention. FIG. 35 shows a sixthembodiment of the invention. FIG. 36 shows a seventh embodiment of theinvention. FIG. 37 shows an eighth embodiment of the invention. FIG. 38shows a ninth embodiment of the invention.

[0112] In the second embodiment, as shown in FIG. 31A, one of thethrough-holes 1 a, through which a shaft (not shown) or a sun gear (notshown) is inserted, is first of all made at the center in one ofpre-flanges (1) of the plate material W formed into a circular shape,and the plate material W is bent and drawn into the shape of a cup.Thereafter, as shown in FIG. 31B, the opening 5 is made in a lowerportion (of the drawing) in the wall 11 of the cup-shaped material W.The groove 4 designed as a bending guide is formed in the innerperiphery of the wall 11 of the material W on the border between thejoint 3 and the other flange 2. Then, as shown in FIG. 31C, the outerperipheral portion of the flange 1 which faces the opening 5 isflattened. As shown in FIG. 31D, the material W is preliminarily closedoff at an appropriate angle from the groove 4 so that the front-endopening of the wall (the outer peripheral end face Wa of the material W)is slightly shrunk radially inwardly by means of spinning or the like.Thereafter, as described above (see FIGS. 19, 20), the closing-offmandrels 12 are inserted from the openings 5 and the material W ispressed. The material W is then closed off so that the front-end openingin the wall 11 (the outer peripheral face Wa of the material W) isshrunk radially inwardly, until the pre-flange (2) becomes parallel tothe flange 1. Thus, the integral-type carrier C is formed so that thejoints 3 for connecting the opposed flanges 1, 2 continue therefrom.

[0113] In the third embodiment, as is the case with the secondembodiment, as shown in FIG. 32A, one of the through-holes la, throughwhich a shaft (not shown) or a sun gear (not shown) is inserted, isfirst of all made at the center in one of pre-flanges (1) of the platematerial W formed into a circular shape, and the plate material W isbent and drawn into the shape of a cup. Thereafter, as shown in FIG.32B, the groove 4 designed as a bending guide is formed in the innerperiphery of the wall 11 of the cup-shaped material W in a portion whichis to be the border between the joints 3 and the flange 2. Then, asshown in FIG. 32C, the material W is preliminarily closed off at anappropriate angle from the groove 4 so that the front-end opening in thewall 11 is slightly shrunk radially inwardly by means of spinning or thelike. Then, as shown in FIG. 32D, the material W is closed off so thatthe front-end opening in the wall 11 (the outer peripheral face Wa ofthe material W) is shrunk radially inwardly, and the integral-typecarrier C is formed so that the joints 3 for connecting the opposedflanges 1, 2 continue therefrom. The openings 5 are thereafter made inthe joints 3 (not shown).

[0114] In the fourth embodiment, as shown in FIG. 33A, one of thethrough-holes la, through which a shaft (not shown) or a sun gear (notshown) is inserted, is first of all made at the center in one ofpre-flanges (1) of the plate material W formed into the shape of a disc,and the openings 5 are made around the through-hole 1 a. Thereafter, theplate material W is bent and drawn into the shape of a cup as shown inFIG. 33B, and the groove 4 designed as a bending guide is formed in theinner periphery of the wall 11 of the cup-shaped material W in a portionwhich is to be the border between the joints 3 and the flange 2. Then,as shown in FIG. 33D, the material W is preliminarily closed off at anappropriate angle from the groove 4 so that the front-end opening in thewall 11 is slightly shrunk radially inwardly by means of spinning or thelike, and the material W is then closed off so that the front-endopening in the wall 11 (the outer peripheral end face Wa of the materialW) is shrunk radially inwardly. Thus, the carrier C is integrally formedso that the joints 3 for connecting the opposed flanges 1, 2 continuetherefrom, as in the aforementioned embodiments.

[0115] Then in the fifth embodiment, as is the case with the fourthembodiment, as shown in FIG. 34A, one of the through-holes la, throughwhich a shaft (not shown) or a sun gear (not shown) is inserted, isfirst of all made at the center in one of pre-flanges (1) of the platematerial W formed into the shape of a disc, and the openings 5 are madearound the through-hole 1 a. Then, as shown in FIG. 34B, the groove 4designed as a bending guide is formed in the inner periphery of the wall11 of the plate material W in a portion which is to be the borderbetween the joints 3 and the flange 2. Then, as shown in FIG. 34C, theplate material W is bent from the groove 4 and drawn into the shape of acup. That is, as long as the bending guide 4 of the invention is formedbefore the material W is closed off, the bending guide 4 may be formedbefore the plate material W is bent and drawn into the shape of a cup.In this embodiment, the wall 11 formed by bending and drawing thematerial W constitutes only the flange 2. Thereafter, as shown in FIG.34D, while the border between the pre-flange (1) and the pre-joints (3)is being bent, the material W is closed off so that the front-endopening in the wall 11 (the outer peripheral end face Wa of the materialW) is shrunk radially inwardly. Thereby the integral-type carrier C isformed so that the joints 3 for connecting the opposed flanges 1, 2continue therefrom.

[0116] Unlike the aforementioned embodiments, a tubular material W isprepared in the sixth embodiment. In this embodiment, as shown in FIG.35A, the openings 5 are first of all made at the axial centers in thetubular material W. Thereafter, the tubular material W is formed intothe shape of a cup by closing off one end thereof as shown in FIG. 35B.Furthermore, as shown in FIG. 35C, the other end Wa of the material W,which is a cup-shaped opening, is closed off, whereby the opposedflanges 1, 2 and the joints for connecting them are integrally formed.Before both the ends of the tubular material W are sequentially closedoff, they are preliminarily closed off as described above. The openings5 may not necessarily be made at the outset. Namely, the openings 5 mayalso be made after one or the other end of the tubular material W hasbeen closed off. Although not shown in this embodiment, a groovedesigned as a bending guide is formed in the inner periphery of thematerial W in a portion which is to be the border between the joints 3and the flange 2. The groove may also be formed in the inner peripheryof the tubular material W in a portion which is to be the border betweenthe flange 1 and the joints 3 before the material W is formed into theshape of a cup by closing off one end thereof to form the flange 1. Asdescribed above, the auxiliary holes 6′, 7′, which are to be theengagement holes 6, 7 for engagement with rotational shafts of planetarygears, may be made in advance in the tubular material W.

[0117] In the seventh embodiment, as is the case with the aforementionedsixth embodiment, the tubular material W with the openings 5 made in itsaxial centers is prepared as shown in FIG. 36A. The seventh embodimentis different from the sixth embodiment in that both the ends Wa of thetubular material W are closed off simultaneously. That is, as shown inFIG. 36B, both the ends Wa of the tubular material W are preliminarilyclosed off at the same time. Furthermore, as shown in FIG. 36C, both theends Wa are closed off simultaneously, whereby the opposed flanges 1, 2are formed. The axial centers of the tubular material W, which are notclosed off, constitute the joints 3 for integrally connecting theflanges 1, 2.

[0118] Unlike the aforementioned embodiment, in the eighth embodiment, arod material W is prepared as shown in FIG. 37A. “The rod material”means a material which has a predetermined length (predeterminedthickness) L in the axial direction of the carrier so as to be formedinto the shape of a cup by backward extrusion or the like and which isthicker than the aforementioned plate material. In this embodiment, asshown in FIG. 37B, the rod material W is first of all formed into theshape of a cup by backward extrusion or the like. Thereafter, as shownin FIG. 37C, one of the through-holes 1 a, through which a shaft (notshown) or a sun gear (not shown) is inserted, is made in the bottom ofthe cup-shaped material W. The cup-shaped opening Wa is then closed off,whereby the opposed flanges 1, 2 and the joints 3 for connecting themare integrally formed as shown in FIG. 37D. The openings 5 among thejoints 3 and the like can be made after the rod material W has beenformed into the shape of a cup.

[0119] In the ninth embodiment, unlike all the aforementionedembodiments wherein the flange 2 or both the flanges 1, 2 are formed byclosing off the material W, the joints 3 are formed by bulging the axialcenters of the tubular material W radially outwardly, and accordingly,the flanges 1, 2 are integrally formed so as to be opposed to each otherand extend from the joints 3 radially inwardly. FIG. 38 shows amechanical bulging machine for bulging the tubular material. In FIG. 38,while the material has not been bulged on the left side with respect toa center line indicated by a chain line, the material has been bulged onthe right side with respect to the center line.

[0120] The bulging machine according to one embodiment of the inventionwill be described with reference to FIG. 38. This bulging machine has anupper mold 50 and a lower mold 51 which are vertically movable relativeto each other, punches 52 for pressing the tubular material W so as tobulge its axial centers, and a cam mechanism 53 for driving the punches52 radially outwardly. In this embodiment, the upper mold 50 issupported by a vertical-drive rod 54 so that the upper mold 50vertically moves relative to the lower mold 51. Receptacles 50 a, 51 afor receiving the tubular material W and cavities 50 b, 51 b fordetermining the configuration of the bulged material are formed in abutt face which is formed when the upper mold 50 and the lower mold 51are closed. The punches 52 are divided in the radial direction of thematerial W and radially slidably supported by punch plates 55 disposedinwardly of the receptacle 50 a of the upper mold 50. A punch holder 56is disposed below the punches 52. A receptacle 57, which receives thepunch holder 56 when the upper mold 50 and the lower mold 51 are buttedagainst each other, is formed inwardly of the receptacle 51 a of thelower mold 51. A stopper 52 a protrudes from a radially intermediateposition on the lower surface of each of the punches 52. Stoppers 56 a,56 b are formed at radially inner and outer positions on the uppersurface of the punch holder 56. A spring 58 is interposed between thestopper 52 a of each of the punches 52 and the radially outer stopper 56a of the punch holder 56 so as to urge each of the punches 52 to retractradially inwardly. The cam mechanism 53 drives each of the punches 52radially outwardly against the urging force of the spring 58 and iscomposed of a cam face 52 b formed radially inwardly of each of thepunches 52 and a cam member 59 bonded to the cam face 52 b. The upperend of the cam member 59 is connected to a drive plate 60. Thevertical-drive rod 54 is inserted through the drive plate 60 so as tovertically drive the drive plate 60 relative to the upper mold 50.

[0121] In the thus-constructed bulging machine, if the drive plate 60 ismoved downwards with respect to the upper mold 50 from the state shownon the left side of FIG. 38, the axial centers of the tubular material Ware pressed outwardly by the cam member 52 and bulged so as to followthe cavities 50 b, 51 b of the upper and lower molds 50, 51. Thus thejoints 3 are formed. At the same time, both the axial ends of thetubular material W constitute a pair of the opposed flanges 1, 2. Thethrough-holes 1 a, 2 a, through which shafts (not shown) and sun gears(not shown) are inserted, are defined by both the end faces Wa of thetubular material W. As can be seen from FIG. 35A and FIG. 36A, the holes5′, which are to be the openings 5, are made in advance in the axialcenters of the tubular material W. In consideration of the fact that theholes 5′ are enlarged radially and axially when the material W isbulged, the dimension of the holes 5′ is set in accordance with thedimension of the openings 5. After the material W has been bulged, thedrive plate 60 is moved upwards with respect to the upper mold 50,whereby the radial end of each of the punches 52 is displaced to aposition inwardly of the through-hole 2 a due to the urging force of thespring 58. Therefore, each of the punches 52 can move away from thecarrier C through the through-hole 2 a as the upper mold 50 ascends.

[0122] The invention is not limited to the aforementioned embodiments.It is possible to employ a hydraulic bulging machine (not shown) insteadof the mechanical one. In this case, a working fluid is supplied into atubular material at a predetermined pressure. Therefore, the tubularmaterial is sealed to prevent the working fluid from leaking out fromthe holes which are made in advance in the axial centers of the tubularmaterial and which are to be the openings 5. Alternatively, the holeswhich are to be the openings 5 are not made in advance in the tubularmaterial, and the openings 5 are made in the material after it has beenbulged.

What is claimed is:
 1. A carrier comprising: a pair of flanges opposedto each other and designed to rotatably support rotating bodies betweenthe flanges; joints that connects the flanges, wherein: the flanges andthe joints are integrally formed through plastic deformation of a singlematerial.
 2. The carrier according to claim 1 , wherein: the joints aredisposed along outer peripheries of the flanges.
 3. The carrieraccording to claim 2 , wherein: openings are made in the joints.
 4. Thecarrier according to claim 1 , wherein: a groove is formed on a borderbetween the flanges and the joints.
 5. The carrier according to claim 1, wherein: through-holes opposed to each other and designed to penetratethe flanges are made on the inner circumferential side of the flanges.6. The carrier according to claim 1 , wherein: engagement holes forengagement with rotational shafts for rotatably supporting rotatingbodies in the carrier are made in the flanges.
 7. A method ofmanufacturing a carrier having a pair of flanges and rotatablysupporting rotating bodies between the flanges, comprising the steps of:forming a material into the shape of a cup having an opening; andclosing off the opening of the cup so that a pair of flanges opposed toeach other and designed to rotatably support rotating bodies between theflanges and joints for connecting the flanges are integrally formed. 8.The method according to claim 7 , wherein: the material is selected froma plate material, a rod material and a tubular material.
 9. The methodaccording to claim 7 , wherein: a bending guide is formed on a borderbetween pre-joints and pre-flanges before the material is closed off.10. The method according to claim 9 , wherein: a groove is formed as thebending guide on a side of the border to which the flanges are opposed.11. The method according to claim 7 , wherein: openings are made inpre-joints of the material before the material is closed off.
 12. Themethod according to claim 11 , wherein: mandrels are inserted from theopenings made in the pre-joints of the material so as to close off thematerial.
 13. The method according to claim 11 , wherein: engagementholes for engagement with rotational shafts for rotatably supportingrotating bodies in the carrier are made in pre-flanges before thematerial is closed off.
 14. The method according to claim 11 , wherein:mandrels are interposed in positions for mounting rotating bodiesbetween the flanges so that the flanges are swaged towards the mandrels.15. The method according to claim 11 , wherein: openings are made in thejoints of the material after the material has been closed off.
 16. Themethod according to claim 11 , wherein: the material is selected from aplate material and a tubular material; and openings are made in thepre-joints of the material before the material is formed into the shapeof a cup.
 17. The method according to claim 11 , wherein: the materialis selected from a plate material and a tubular material; and a bendingguide is formed on a border between pre-joints and a pre-flange of thematerial before the material is formed into the shape of a cup.
 18. Themethod according to claim 17 , wherein: a groove is formed as thebending guide on a side of the border to which the flanges are opposed.19. The method according to claim 11 , wherein: a bottom of the materialformed into the shape of the cup is turned into a first flange;peripheral walls adjacent to the bottom are turned into joints; and anopening-side portion of the cup-shaped material, which is to be closedoff, is turned into a second flange.
 20. A method of manufacturing acarrier having a pair of flanges and rotatably supporting rotatingbodies between the flanges, comprising the steps of: preparing a tubularmaterial; closing off both end openings of the tubular material so thata pair of flanges opposed to each other and designed to rotatablysupport rotating bodies between the flanges and joints for connectingthe flanges are integrally formed.
 21. The method according to claim 20, wherein: a bending guide is formed on a border between pre-joints andpre-flanges before the material is closed off.
 22. The method accordingto claim 21 , wherein: a groove is formed as the bending guide insidethe tube on the border.
 23. The method according to claim 20 , wherein:openings are made in pre-joints of the material before the material isclosed off.
 24. The method according to claim 20 , wherein: mandrels areinserted from the openings made in the pre-joints of the material so asto close off the material.
 25. The method according to claim 20 ,wherein: engagement holes for engagement with rotational shafts forrotatably supporting rotating bodies in the carrier are made inpre-flanges before the material is closed off.
 26. The method accordingto claim 20 , wherein: mandrels are interposed in positions for mountingrotating bodies between the flanges so that the flanges are swagedtowards the mandrels.
 27. The method according to claim 20 , wherein:axial centers of a side wall of the tubular material are turned into thejoints; and both axial ends of the side wall of the tubular material,which are to be closed off, are turned into a pair of flanges.
 28. Amethod of manufacturing a carrier having a pair of flanges and rotatablysupporting rotating bodies between the flanges, comprising the steps of:preparing a tubular material having a tubular wall surface; bulging awall surface at the axial center of the tubular material radiallyoutwardly so that a pair of flanges opposed to each other and designedto rotatably support rotating bodies between the flanges and joints forconnecting the flanges are integrally formed.
 29. The method accordingto claim 28 , wherein: openings are made in pre-joints of the materialbefore the material is closed off.
 30. The method according to claim 28, wherein: engagement holes for engagement with rotational shafts forrotatably supporting rotating bodies in the carrier are made inpre-flanges before the material is closed off.
 31. The method accordingto claim 28 , wherein: mandrels are interposed in positions for mountingrotating bodies between the flanges so that the flanges are swagedtowards the mandrels.
 32. The method according to claim 28 , wherein:axial centers of the bulged side wall are turned into the joints; andboth axial ends of the side wall of the tubular material, which are tobe closed off, are turned into a pair of flanges.